As the number of recommended preventive services continues to increase, clinicians struggle to maintain a balance between immediate patient concerns and the time required to address prevention. It is clear that without effective and timely clinical decision support integrated into a comprehensive care delivery approach (e.g. the Chronic Care Model) and without patient-centered tailoring of recommendations, primary care clinicians'performance in this area is likely to go from suboptimal (40-60% rates of delivery of well-accepted preventive services) to unsatisfactory. Optimal delivery of primary, secondary, and tertiary preventive services will increasingly require sophisticated information processing and much greater patient involvement. Despite the importance of patient-centered delivery approaches, however, there is limited information available on the impact of integrated health information technologies (HIT) on the delivery of patient centered, preventive care in primary care settings. Building upon our experience with a very sophisticated preventive services prompt and reminder system, the Preventive Services Reminder System (PSRS), we propose to conduct a systematic three-year study with the following aims: 1) To develop, field test, and refine an Internet-based patient Wellness Portal linked to PSRS to facilitate patient-centered, preventive care in primary care practices;2) To determine the impact of the Wellness Portal on the process of patient-centered preventive care by examining the behavior and experiences of both patients and providers and the degree to which recommended services are individualized;and 3) To develop model Wellness Portal practices and disseminate the Wellness Portal technology and knowledge derived from findings from Aims 1 and 2. As a result of the Wellness Portal approach, we expect that activated patients and transformed medical practices will be more likely to engage in proactive, patient-centered care, and that this will result in more consistent delivery of appropriate preventive services to the right patients at the right times.